This invention relates to medical fluid infusion and aspiration.
Infusion of fluid into the body or aspiration of fluid from the body is often performed with a catheter which is inserted beneath the skin. The catheter has a lumen through which fluid can flow. In some designs, the lumen is closed at the insertion end of the catheter and fluid communication between the body environment outside the catheter and the lumen is controlled by a slit through the catheter wall which acts as a valve. The catheter has a hub on the end outside the body which can be connected to a syringe for increasing and decreasing the pressure inside the lumen.
For infusion, the fluid pressure inside the lumen is increased to force the catheter body adjacent the slit to flex outward, separating the opposing faces of the slit and forming an aperture through which fluid may pass to the body environment. For aspiration, the pressure inside the lumen is decreased to force the catheter body adjacent the slit to collapse inward, forming an aperture through which fluid may flow into the lumen. At neutral pressures, the catheter body assumes an unflexed condition in which the faces of the slit are opposed, which forms a seal to prevent infusion or aspiration.
A valve can be made to permit infusion only, aspiration only, or both infusion and aspiration. A valve that operates for infusion only can be formed by making the slit in a convex catheter wall portion, since the convex shape facilitates flexing outward while resisting flexing inward. A valve that operates for aspiration only can be formed by making the slit in a concave wall portion, which facilitates flexing inward while resisting flexing outward. A flat wall portion facilitates flexing in either direction and can be used to form a two-direction valve.
A two-direction valve may also be formed by chemical weakening of the catheter wall adjacent the slit, which facilitates flexing in both directions so that the valve works smoothly during infusion and aspiration. The lumen may also be shaped with a linear side that terminates to form regions of reduced catheter wall thickness. The regions act as hinges at which inward and outward flexing is enhanced and the area between the regions may have a greater wall thickness which facilitates sealing.
The catheter may also have multiple valves and multiple lumens. Further discussion of catheters is found, for example, in Groshong U.S. Pat. No. 4,549,879, Nichols U.S. Pat. No. 4,753,640, Lui U.S. Pat. No. 5,261,885, and Luther U.S. Pat. No. 5,522,807 the entire contents of all of which are incorporated herein by reference.
In one aspect, the invention features a slit valve catheter with an elongated, generally tubular catheter body having an exterior surface exposed to an environment and an interior surface defining a lumen. The catheter further includes a valve which has a protuberance projecting from the catheter body and a slit through the protuberance and catheter body.
In another aspect, the invention features a slit valve catheter having an elongated, generally tubular catheter body with an exterior surface exposed to an environment and an interior surface defining a lumen. The catheter further includes a valve with a generally convex exterior surface portion and a protuberance projecting radially outward from the convex exterior surface portion into the environment and a slit through the protuberance and catheter body. The interior surface defines a generally concave interior wall portion opposite the convex exterior surface portion.
In another aspect, the invention features a slit valve catheter with an elongated, generally tubular catheter body having an exterior surface exposed to an environment and an interior surface defining a lumen. The catheter further includes a valve with a generally concave exterior surface portion and a protuberance projecting radially inward from the interior surface opposite the concave exterior surface portion and a slit through the protuberance and catheter body and having a generally uniform wall thickness between the interior and exterior surface in portions adjacent the protuberance.
In another aspect, the invention features a slit valve catheter, having an elongated, generally tubular catheter body with an exterior surface exposed to an environment and an interior surface defining a lumen. The catheter further includes a first valve and a second valve. The first valve includes a protuberance projecting radially from the catheter body and a slit through the protuberance and catheter body.
In another aspect, the invention features a slit valve catheter with an elongated, generally tubular catheter body having an exterior surface exposed to an environment and an interior surface defining a first lumen and a second lumen. The catheter further includes a first valve to the first lumen which has a protuberance projecting radially from the catheter body and a slit through the protuberance and catheter body to the first lumen.
In another aspect, the invention features infusing fluid into a body or aspirating fluid from a body by delivering into the body a catheter having a generally elongated catheter body including an exterior surface exposed to the body and an interior surface defining a lumen. The catheter further includes an aspiration valve and an infusion valve, where at least one of the valves includes a protuberance projecting from the catheter body for permitting one of aspiration or infusion while resisting one of infusion or aspiration. The pressure in the lumen is varied to effect infusion or aspiration.
Embodiments may include one or more of the following features. The protuberance has a radial projection no greater than the outer diameter of the catheter body. The protuberance has a width no greater than twice a thickness of the catheter body measured between the exterior surface and the interior surface at a region adjacent the protuberance. The protuberance has a geometrical inflection near its point of maximum projection. (A geometrical inflection is the region where the curvature of the catheter (viewed in cross-section) changes from concave to convex or conversely, or the region in which the slope of a line tangent to the curvature is zero and the slope of lines adjacent the region have different signs.) The protuberance has a pair of inflections near the circumferential boundary of the protuberance. The protuberance is generally hemispherical. The protuberance is an integral extension of the catheter body. The protuberance extends axially no further than the valve. The protuberance extends axially substantially the length of the catheter body. The valve is on a sidewall of the catheter. The valve is on a forward-facing distal tip of the catheter.
Embodiments may also include one or more of the following. The valve includes a region having a convex exterior surface portion and the protuberance projects outwardly from the convex portion into the environment. The valve includes a region having a convex exterior surface portion and the protuberance projects inwardly from an interior surface portion opposite the convex surface portion. The valve includes a region having a concave exterior surface portion and the protuberance projects outwardly from the portion into the environment. The valve includes a region having a concave exterior surface portion and the protuberance projects inwardly from an interior surface portion opposite the concave exterior surface portion. The valve includes a region having a generally flat exterior surface portion and the protuberance projects outwardly from the flat exterior surface portion. The valve includes a region having a generally flat exterior surface portion and the protuberance projects inwardly from an interior surface portion opposite the flat exterior surface portion. The interior surface portion is generally flat. The catheter includes a first protuberance projecting from the exterior surface and a second protuberance projecting from the interior surface portion generally opposite the first protuberance. The radial projection of the first protuberance is different than the radial projection of the second protuberance.
Embodiments may also include one or more of the following. The interior surface is generally circular in cross-section. The exterior surface is generally circular in cross-section. The catheter has a generally uniform wall thickness between the interior and exterior surface in portions adjacent the protuberance.
Embodiments may also include one or more of the following. The catheter has a second valve and the second valve has a protuberance projecting radially from the catheter body and a slit through the protuberance and catheter body. The protuberance on the first valve projects from the exterior surface of the catheter into the environment and the protuberance on the second valve projects from the interior surface of the catheter body into the lumen. The first valve is proximal of the second valve. The second valve is on a forward-facing distal tip of the catheter. The slit catheter has a second valve to the first lumen. The catheter has a third valve to a second lumen.
Embodiments may also include one or more of the following. Both an aspiration and infusion valve are in communication with the same lumen and each include a protuberance. The protuberance on the aspiration valve being arranged to resist infusion and the protuberance on the infusion valve is arranged to resist aspiration. Alternately infusion and aspirating fluid from the body by increasing and delivering pressure in the lumen. The catheter may be delivered into the body over a guidewire.
Implementations may provide one or more advantages. For example, the protuberance may reduce leaks through the valve, especially leaks due to unintended valve openings when pressure conditions in the lumen are opposite to the intended valve operation direction. The protuberance can also control the level of lumen pressure needed to open the valve. The protuberance valves may be used on very thin-walled catheters in which the wall thickness is not sufficient to create an effective seal. A thinner catheter wall can provide a larger lumen, which may permit greater infusion and aspiration flow rates without substantially increasing the overall catheter diameter or the pressure differential needed to operate the valve.
Further aspects, features, and advantages follow.